* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
            line-height: 1.6;
            color: #1a1a1a;
            background: #ffffff;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 40px;
        }

        /* Page Management */
        .page {
            display: none;
        }

        .page.active {
            display: block;
        }

        /* Navigation */
        .nav-bar {
            background: #ffffff;
            border-bottom: 2px solid #000000;
            padding: 20px 0;
            position: sticky;
            top: 0;
            z-index: 1000;
        }

        .nav-container {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: #000000;
            cursor: pointer;
        }

        .nav-links {
            display: flex;
            gap: 30px;
        }

        .nav-link {
            color: #666666;
            text-decoration: none;
            font-weight: 500;
            padding: 10px 15px;
            border-radius: 4px;
            transition: all 0.3s ease;
            cursor: pointer;
        }

        .nav-link:hover, .nav-link.active {
            color: #000000;
            background: #f5f5f5;
        }

        .back-btn {
            background: #000000;
            color: #ffffff;
            border: none;
            padding: 10px 20px;
            border-radius: 4px;
            cursor: pointer;
            font-weight: 500;
            transition: all 0.3s ease;
        }

        .back-btn:hover {
            background: #333333;
        }

        /* Header */
        .header {
            background: #000000;
            color: #ffffff;
            padding: 80px 0;
            position: relative;
        }

        .header::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 100%;
            height: 1px;
            background: linear-gradient(90deg, transparent, #333, transparent);
        }

        .header-content {
            text-align: center;
            max-width: 800px;
            margin: 0 auto;
        }

        .profile-image {
            width: 150px;
            height: 150px;
            border-radius: 50%;
            border: 4px solid #ffffff;
            margin: 0 auto 30px;
            background: #333333;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 3rem;
            color: #ffffff;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .profile-image:hover {
            border-color: #cccccc;
            transform: scale(1.05);
        }

        .image-upload {
            display: none;
        }

        .profile-image img {
            width: 100%;
            height: 100%;
            border-radius: 50%;
            object-fit: cover;
        }

        .header h1 {
            font-size: 3.5rem;
            font-weight: 300;
            letter-spacing: -2px;
            margin-bottom: 15px;
        }

        .header .title {
            font-size: 1.4rem;
            font-weight: 400;
            color: #cccccc;
            margin-bottom: 30px;
            letter-spacing: 1px;
            text-transform: uppercase;
        }

        .header .description {
            font-size: 1.1rem;
            color: #999999;
            max-width: 600px;
            margin: 0 auto 40px;
            line-height: 1.7;
        }

        .contact-bar {
            display: flex;
            justify-content: center;
            gap: 40px;
            margin-top: 40px;
            padding-top: 30px;
            border-top: 1px solid #333333;
        }

        .contact-item {
            color: #cccccc;
            text-decoration: none;
            font-size: 0.95rem;
            transition: color 0.3s ease;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .contact-item:hover {
            color: #ffffff;
        }

        /* Main Content */
        .main {
            background: #ffffff;
            padding: 80px 0;
        }

        .section {
            margin-bottom: 80px;
        }

        .section:last-child {
            margin-bottom: 0;
        }

        .section-title {
            font-size: 2.2rem;
            font-weight: 600;
            color: #000000;
            margin-bottom: 50px;
            text-align: center;
            position: relative;
        }

        .section-title::after {
            content: '';
            position: absolute;
            bottom: -15px;
            left: 50%;
            transform: translateX(-50%);
            width: 60px;
            height: 2px;
            background: #000000;
        }

        /* Clickable Items */
        .clickable-item {
            cursor: pointer;
            transition: all 0.3s ease;
            padding: 20px;
            margin: -20px;
            border-radius: 8px;
        }

        .clickable-item:hover {
            background: #f8f8f8;
            transform: translateX(10px);
        }

        /* Experience */
        .experience-item {
            border-left: 2px solid #000000;
            padding-left: 30px;
            margin-bottom: 40px;
            position: relative;
        }

        .experience-item::before {
            content: '';
            position: absolute;
            left: -6px;
            top: 0;
            width: 10px;
            height: 10px;
            background: #000000;
            border-radius: 50%;
        }

        .experience-header {
            margin-bottom: 15px;
        }

        .experience-title {
            font-size: 1.3rem;
            font-weight: 600;
            color: #000000;
            margin-bottom: 8px;
        }

        .experience-company {
            color: #666666;
            font-weight: 500;
            margin-bottom: 5px;
        }

        .experience-period {
            background: #f5f5f5;
            padding: 4px 10px;
            border-radius: 4px;
            font-size: 0.85rem;
            color: #333333;
            display: inline-block;
            font-weight: 500;
        }

        .experience-description {
            margin-top: 15px;
        }

        .experience-description ul {
            list-style: none;
        }

        .experience-description li {
            position: relative;
            padding-left: 20px;
            margin-bottom: 8px;
            color: #444444;
            line-height: 1.6;
        }

        .experience-description li::before {
            content: '—';
            position: absolute;
            left: 0;
            color: #999999;
        }

        .view-details {
            margin-top: 15px;
            color: #000000;
            font-weight: 600;
            text-decoration: underline;
            font-size: 0.9rem;
        }

        /* Projects */
        .project-item {
            background: #ffffff;
            border: 2px solid #000000;
            padding: 40px;
            margin-bottom: 30px;
            transition: all 0.3s ease;
            cursor: pointer;
        }

        .project-item:hover {
            background: #000000;
            color: #ffffff;
        }

        .project-title {
            font-size: 1.4rem;
            font-weight: 600;
            margin-bottom: 15px;
        }

        .project-description {
            margin-bottom: 20px;
            line-height: 1.7;
            opacity: 0.9;
        }

        .project-details ul {
            list-style: none;
        }

        .project-details li {
            position: relative;
            padding-left: 20px;
            margin-bottom: 8px;
            line-height: 1.6;
            opacity: 0.8;
        }

        .project-details li::before {
            content: '▸';
            position: absolute;
            left: 0;
            opacity: 0.6;
        }

        /* Detail Pages */
        .detail-header {
            background: #000000;
            color: #ffffff;
            padding: 60px 0;
        }

        .detail-title {
            font-size: 2.5rem;
            font-weight: 600;
            margin-bottom: 20px;
        }

        .detail-subtitle {
            font-size: 1.2rem;
            color: #cccccc;
            margin-bottom: 10px;
        }

        .detail-period {
            color: #999999;
            font-size: 1rem;
        }

        .detail-content {
            padding: 60px 0;
        }

        .detail-section {
            margin-bottom: 50px;
        }

        .detail-section h3 {
            font-size: 1.5rem;
            font-weight: 600;
            color: #000000;
            margin-bottom: 20px;
            border-bottom: 2px solid #f0f0f0;
            padding-bottom: 10px;
        }

        .detail-list {
            list-style: none;
            margin: 20px 0;
        }

        .detail-list li {
            position: relative;
            padding-left: 25px;
            margin-bottom: 15px;
            line-height: 1.7;
            color: #444444;
        }

        .detail-list li::before {
            content: '●';
            position: absolute;
            left: 0;
            color: #000000;
        }

        .tech-stack {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            margin: 20px 0;
        }

        .tech-tag {
            background: #000000;
            color: #ffffff;
            padding: 8px 15px;
            border-radius: 20px;
            font-size: 0.9rem;
            font-weight: 500;
        }

        /* Education, Skills, Certifications */
        .education-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
            gap: 30px;
            margin-top: 50px;
        }

        .education-item {
            background: #000000;
            color: #ffffff;
            padding: 35px;
            border-radius: 0;
            position: relative;
            transition: transform 0.3s ease;
        }

        .education-item:hover {
            transform: translateY(-5px);
        }

        .education-degree {
            font-size: 1.2rem;
            font-weight: 600;
            margin-bottom: 15px;
            line-height: 1.4;
        }

        .education-school {
            color: #cccccc;
            margin-bottom: 10px;
            font-size: 0.95rem;
        }

        .education-period {
            color: #999999;
            font-size: 0.9rem;
            font-weight: 500;
        }

        .skills-container {
            margin-top: 50px;
        }

        .skills-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 40px;
        }

        .skill-group {
            text-align: center;
        }

        .skill-group h4 {
            font-size: 1.2rem;
            font-weight: 600;
            color: #000000;
            margin-bottom: 25px;
            text-transform: uppercase;
            letter-spacing: 1px;
        }

        .skill-items {
            display: flex;
            flex-direction: column;
            gap: 12px;
        }

        .skill-item {
            background: #f8f8f8;
            padding: 12px 20px;
            border-left: 3px solid #000000;
            font-weight: 500;
            color: #333333;
            transition: all 0.3s ease;
        }

        .skill-item:hover {
            background: #000000;
            color: #ffffff;
        }

        .certifications {
            background: #f8f8f8;
            padding: 80px 0;
            margin-top: 80px;
        }

        .cert-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
            margin-top: 50px;
        }

        .cert-item {
            background: #ffffff;
            padding: 30px;
            text-align: center;
            border: 1px solid #e0e0e0;
            transition: all 0.3s ease;
        }

        .cert-item:hover {
            border-color: #000000;
            transform: translateY(-3px);
        }

        .cert-item h4 {
            font-size: 1.1rem;
            font-weight: 600;
            color: #000000;
            margin-bottom: 10px;
        }

        .cert-item p {
            color: #666666;
            font-size: 0.95rem;
        }

        .languages {
            margin-top: 60px;
            text-align: center;
        }

        .languages h3 {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 30px;
            color: #000000;
        }

        .language-grid {
            display: flex;
            justify-content: center;
            gap: 60px;
        }

        .language-item {
            text-align: center;
        }

        .language-item strong {
            display: block;
            font-size: 1.1rem;
            color: #000000;
            margin-bottom: 5px;
        }

        .language-level {
            color: #666666;
            font-size: 0.9rem;
        }

        .footer {
            background: #000000;
            color: #ffffff;
            text-align: center;
            padding: 60px 0;
        }

        .footer p {
            color: #cccccc;
            font-size: 0.9rem;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .container {
                padding: 0 20px;
            }

            .nav-links {
                gap: 15px;
            }

            .header h1 {
                font-size: 2.5rem;
            }

            .header .title {
                font-size: 1.1rem;
            }

            .contact-bar {
                flex-direction: column;
                gap: 20px;
                text-align: center;
            }

            .section-title {
                font-size: 1.8rem;
            }

            .education-grid {
                grid-template-columns: 1fr;
            }

            .skills-grid {
                grid-template-columns: 1fr;
            }

            .language-grid {
                flex-direction: column;
                gap: 30px;
            }

            .main, .certifications {
                padding: 60px 0;
            }

            .section {
                margin-bottom: 60px;
            }

            .detail-title {
                font-size: 2rem;
            }
        }